Mopalia hindsii (Sowerby in Reeve, 1847)
Common name(s): Hind's chiton
|Synonyms: (Listed as Mopalia hindsi in some references)|
|Mopalia hindsii feeding on the sponge Myxilla incrustans which is growing on the shell of the scallop Chlamys hastata.|
|(Photo by: Dave Cowles, July 2007)|
How to Distinguish from Similar Species: Mopalia muscosa has dense, straplike hairs on the girdle. Mopalia lignosa has more hairs on the girdle and has no obvious rows of raised tubercles on the plates (but it does have pits), plus the posterior cleft in the girdle is absent or very small and the ventral girdle is orange. Neither M. muscosa nor M. lignosa has a prominent posterior cleft in the girdle. Mopalia ciliata does have a prominent posterior girdle cleft but its girdle hairs are strap-shaped, have glassy spicules, and branch other than at the base.
Geographical Range: SE Alaska to Ventura, CA. This species is said to be very common in California but is not often mentioned in guides to the Pacific Northwest.
Depth Range: Intertidal (and subtidal?)
Habitat: Common intertidally under rocks, both on outer coast and in bays.
Biology/Natural History: This species
feeds on filamentous algae, diatoms, polychaetes, amphipods, and barnacles
(and apparently on sponges). It is common on shaded pilings, where
the valves are often overgrown by bryozoans, annelids, barnacles, and hydroids.
The reproductive cycle is variable but in California it is mainly from
October to March. It does not brood its young. It may
have the flatwormNexilis epichitonius
symbiotic in its mantle cavity.
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Morris et al., 1980
O'Clair and O'Clair, 1998
Ricketts et al., 1985
General Notes and Observations: Locations,
abundances, unusual behaviors:
This larger view shows how the chiton is grazing the sponge off the
This closeup shows the detail on the plates, plus a view of some of the girdle.
The anterior two plates of this individual have a lot of white.
This closeup of some of the sparse girdle hairs, along the lateral margin of the girdle, shows how the larger hairs branch from the base. The orange/pink background is the sponge and scallop that the chiton is crawling on. Other than on these lateral areas and in some areas along the edges of the plates the girdle hairs are quite sparse.
This closeup is of some girdle hairs which are not right at the margin of the girdle.
The underside of the girdle of this species is not orange.